Sealing joints

[Lakesailor]

Serious question for the panel. I've put this on PBO as well.
I'm restoring a Heron dinghy for fun and put it the water the other night to see where it leaks.
I was expecting the centreboard casing to leak (they always seem to) and it didn't disappoint.
Turning it on its side and looking up into the casing I can see that parts of the various layers of sealers and mastics that have built up over the years (50) have come away leaving the casing/keel joint exposed in places. I can easily rake out and dry the joints but want opinions on the best method of sealing.
I tend towards drizzling epoxy into the joint and then topping with a layer of epoxy/ceramic beads mix.
Would Sikaflex form a seal. I've only ever had success with it when it's been in compression, not just as a surface bead.

What does the team think?

 

[Peterduck]

Tape the outside of the case at the joint with the logs before turning the boat on its side. Use duct tape or something similar. Run a thin epoxy such as Epiglass' Everdure in to the seam. This will ensure good penetration, and the tape should prevent any loss of resin through excessive leakage. Some will leak through, and this will tell you where the worst leaks are. also brush the epoxy along the seam with the end posts. Follow this up with a thicker epoxy trowelled in, and pushed into the crack as hard as possible. Remember that you are trying to avoid bubbles forming. Pay particular attention to the corners with the fore and aft posts. Turn the boat over and repeat for the other side. Smooth the surface of the epoxy once it has cured with abrasive paper or a file. I would also look at the feasibility of laying a strip of woven roving saturated in epoxy over the seam as well, as a sort of 'belt-and-braces' approach. if there is sufficient gap between the centreboard and the case sides.
Peter.

 

[Mirelle]

Thanks for that; I have been contemplating the same problem on our Firefly!

 

[Lakesailor]

Thanks. I've made a start on the worst side. The epoxy has just manged to run through to the other side of the joint, which I've taped with masking tape.
The end posts are more awkward as you suggest, but some ceramic beads added allowed me to brush up the gap without it running out again.
I've actually managed to get a very smooth finish by adjusting the angle of the boat until the epoxy flowed nicely over the repair area. I'm using a slow cure epoxy.
Just have to turn it onto it's other side and repeat.
There isn't really room for mat, but I think this may have cracked it.